It is not known if the winning bidder is linked to state-controlled Gazprom, or if it represents private investors.

Foreign investors in Yukos tried to block the sale in U.S. court. But Russia ignored the American ruling and proceeded with the auction aimed at paying-off some of the more than $27 billion Yukos owes in back taxes.

The company's legal troubles are widely seen as a government move against former Yukos head Mikhail Khodorkovsky, who supported political opponents of Russian President Vladimir Putin. The oil tycoon is currently in jail in Russia, awaiting trial on fraud and tax evasion charges.